Low gloss thermoformable flooring structure

ABSTRACT

A novel flooring composition was developed based on a blend comprising: a) an elastomer; b) a random propylene/alpha-olefin copolymer; c) a cross linking agent; and optionally d) a melt strength enhancing polymer. This composition achieves a unique balance of properties, exhibiting often-conflicting performance requirements. These include low gloss and excellent pattern duplication in embossing, low modulus, minimal odor, excellent grain acceptance and abrasion resistance, while remaining thermoformable and maintaining minimal shift in viscosity during recycle.

The present application is 35 U.S.C. §371 National Stage ofInternational Application No. PCT/U504/09501, filed on Mar. 26, 2004,which claims the benefit of U.S. Provisional Application No. 60/458,517,filed on Mar. 28, 2003.

Many polymer-processing methods involve the application of temperatureand pressure to a resin formulation to fabricate a specific part.Examples of such processes include thermoforming, blow molding,injection molding and overmolding, calendaring, fiber forming, wire andcable, and extrusion coating. The parts resulting from these processesare often required to exhibit a variety of often-conflicting propertiesand thus industry is always looking for new formulations able to exhibita desired combination of properties for a given processing method.

A variety of blend compositions have been formulated in an attempt tomeet the requirements of the various molding processes. For instance,U.S. Pat. No. 5,639,818 describes a peroxide modified propylenehomopolymer/polyethylene blend that exhibit superior extrusion coatingproperties, especially increased melt strength and reduced drawresonance behavior rendering them suitable for a wide variety ofapplications including thermoforming, blow molding as well as extrusioncoating.

U.S. Pat. No. 6,433,062 B1 describes a process for the preparation of athermoplastic elastomeric composition by melt kneading an organicperoxide with a mixture of a block copolymer (or hydrogenated blockcopolymer), a non-aromatic softening agent for rubber, an ethylenehomopolymer or copolymer, and a propylene homopolymer or copolymer. Theresulting composition exhibits improved heat deformation resistance,mechanical strength, moldability and processability.

U.S. Pat. No. 6,407,172 B1 describes a composition suitable forthermoforming, which demonstrates good grain retention and low cost. Thecomposition comprises a mixture of a propylene homopolymer or copolymer,an ethylene-containing ionomer, a copolymer of ethylene and a glycidylacrylate, polyethylene, optionally an uncrosslinked ethylene/propylenecopolymer rubber, and optionally an ethylene alpha-olefin copolymerelastomer.

US Patent Application Publication No. 2001/0016620 A1 describes acrosslinked olefin thermoplastic composition comprising a crystallinepolyolefin, an olefin-based copolymer rubber, and a paraffinic mineraloil softening agent which after molding results in articles withimproved antifogging properties and high gloss.

U.S. Pat. No. 6,407,172 B1 describes thermoplastic polymer alloycomposition comprising a blend of polypropylene, uncrosslinked ethylenecopolymer, an ionomeric copolymer of ethylene and an α,β-unsaturatedcarboxylic acid, a crosslinking agent and a silicone elastomer. Thecompositions are said to be useful for forming interior skin sheets forapplications where low gloss and high scuff resistance are desired.

U.S. Pat. No. 6,451,894 B1 describes molded articles made fromthermoplastic blends of a crystalline or semi crystalline polyolefin anda multimodal elastomer of sequentially polymerized ethylene/alpha olefinmonomers. Molded articles made from such blends exhibit increased paintadherence and improved resistance to fluid as well as higher weld linestrength and low temperature ductility.

U.S. Pat. No. 6,506,842 B1 describes a rheology-modified thermoplasticelastomer composition. The composition is prepared byperoxide-modification of a melt blend of an ethylene/alpha-olefincopolymer or a diene-modified ethylene/alpha-olefin copolymer and a highmelting point polymer such as a polypropylene or a propylene/alphaolefin. The composition is peroxide modified sufficient to result in anincrease in solidification temperature (that is, the temperature of thehighest temperature peak endotherm measured during cooling bydifferential scanning calorimeter (DSC)) that is at least 10° C. greaterthan that of the unmodified composition. These compositions haveimproved heat resistance and thus must be processed at highertemperatures.

Finally, US Patent Application Publication No. 2002/0115796 A1 describesthermoplastic elastomer compositions comprising a melt blend of anethylene/alpha-olefin copolymer and a high melting point polymer such asa polypropylene or a propylene/alpha which is rheology modified using acombination of a peroxide and free radical coagents. The use of thecoagent is said to increase the melt toughness and high temperaturetensile properties as compared to the same compositions, which arerheology modified by peroxides alone.

Thermoforming is another of the family of processes that deal with thepressing or squeezing of pliable plastic into a final shape, and is thegeneral term used for the process of making plastic parts from a flatsheet of plastic, through the application of pressure and temperature.However, thermoforming is differentiated from extrusion or blow molding,as in the former, the initial resin state is fluid rather than solid,whereas thermoforming always begins with a contiguous sheet of rubberyplastic. This sheet has been processed from resin pellets or powder bycasting, calendaring, rolling, extruding, compression molding or othertechniques. The thermoforming process is a result of four subsequentsteps, namely; 1) heating the sheet, 2) stretching it; 3) cooling it onthe mold surface; and 4) trimming the resulting part from itssurroundings

These deformation processes must occur while the polymer is in a rubberysolid state that is, above its glass transition temperature (Tg) butbelow its crystalline melting temperature (Tm) allowing easy uptake ofthe mold configuration. Thus the glass transition temperature, Tg, isthe absolute lowest temperature at which the polymer can be formed. Asprocessing temperatures increase above Tg, amorphous polymers becomeincreasingly easier to process, but in crystalline polymers, thecrystallite order restricts amorphous phase chain morphology, until themelting point is reached. Thus the normal thermoforming or “forming”temperature for an amorphous polymer is closely related to Tg, but forcrystalline polymers the forming temperature is more dependent on theTm. Typically, for single component amorphous materials, the lowerforming temperature is about 20-30° C. above Tg, and the normal formingtemperature is 70-100° C. above Tg. In contrast, the forming temperaturerange for crystalline polymers is quite narrow and the recommendedforming temperature is often within a few degrees of the polymer Tm.

Once the plastic sheet is at the proper thermoforming temperature it canbe stretched. The various thermoplastic sheet-forming techniquesinclude, vacuum forming, pressure forming, matched mold forming, all ofwhich require clamping, heating and shaping the sheet into or over amold. Before forming, the heated sheet is virtually stress free. Whenproperly formed, the sheet is almost completely stretched at the formingtemperature before it is cooled against the mold. This results in aminimum of internal stress in the finished part.

In order to be readily formable, the heated sheet, when at formingtemperature, must have certain physical properties including high meltstrength, over a broad temperature range. The physical properties andmelt strength of some thermoplastic polymers can be improved by the useof crosslinking agents, including peroxide and irradiation. A smallamount of crosslinking serves to partially immobilize the polymer whileabove its traditional melting point by the introduction of a smallamount of ultra high molecular weight material within the bulk polymermatrix resulting in an increase in the low shear viscosity and storagemodulus. Thus, instead of becoming fluids above their melting points,lightly crosslinked thermoplastics remain soft thermoformable solidsextending the range of the thermoforming temperature for such materials.However, too high a degree of crosslinking restricts the type of grossdeformation required for successful thermoforming.

In addition to having the necessary strength requirements for moldingthe heated sheet, many applications require the resulting article to beembossed and also exhibit a specific gloss level. The degree of glosscan be regulated to some degree by the processing conditions such asextrudate or sheet temperature. Low gloss usually results from lowextrudate or sheet temperature. In addition, while remaining relativelyconstant up to a certain thermoforming temperature, above thistemperature, gloss begins to increase exponentially with furthertemperature increase. However, embossability increases much morelinearly across the same temperature range.

The introduction of crosslinking in a polymer causes a decrease in thelevel of gloss of a finished part as a small amount of ultra highmolecular weight material within the bulk polymer matrix causesdistortions in the surface on cooling which in turn leads to a lowersurface gloss. These distortions are due to the increased relaxationtime of the ultra high molecular weight fraction relative to the bulkpolymer matrix.

Flooring applications such as automotive flooring mats and liners havehistorically required the use of polymer compositions that exhibit bothgood thermoformability and excellent embossing pattern retention.Furthermore, such applications also generally require low surface glossof the flooring for aesthetics and non-marking performance attributes.Recently, industry has developed the additional needs that suchcompositions also exhibit improved softer hand feel.

To date, typical polymer formulations used for such applications aremade primarily of thermoplastic polyolefin (TPO) with polypropylene asthe major component of the polymeric blend. Polypropylene is used as ithas good abrasion resistance and thermal dimensional stability (that is,very important in automotive applications, which often require a hightemperature dimensional stability and abrasion resistance). Flooringthat is thermoformed from such compositions typically exhibit goodthermoformability with excellent embossability. However, the flooringhas relatively high stiffness.

Therefore it would be highly advantageous if new polymer compositionscould be discovered which typically exhibit good thermoformability andexcellent embossability and also exhibit low surface gloss foraesthetics and non-marking performance attributes.

The present invention relates to thermoplastic polymer compositions,articles made from such compositions, which exhibit theoften-conflicting performance requirements of low gloss and excellentpattern duplication in embossing, while also exhibiting low modulus,minimal odor issues, excellent grain acceptance and abrasion resistanceand maintained minimal shift in viscosity during recycle. Whileapplicable to all molding and other processes requiring low gloss, thecompositions of the present invention are especially suitable forthermoforming due to the range of processing temperatures used relativeto the onset of high gloss. In addition, the ability to control glossand embossability is especially important for thermoforming, which hasno opportunity for additional process steps to reduce gloss other thanpolymer composition or temperature variation within the thermoformingwindow.

Novel flooring compositions have been developed based on a blendcomprising; A) an elastomer; B) a random propylene/alpha-olefincopolymer; C) a cross linking agent; and optionally D) a melt strengthenhancing polymer. This composition achieves a unique balance ofproperties. The final blend composition surprisingly exhibits theoften-conflicting performance requirements of low gloss and excellentpattern duplication in embossing, while also exhibiting low modulus,minimal odor issues, excellent grain acceptance and abrasion resistanceand maintained minimal shift in viscosity during recycle remainingthermoformable.

The cross linking agent generates a small amount of ultra high molecularweight material which increases its storage modulus and its low shearviscosity allowing the polymer to remain rubbery, at a given formingtemperature. In addition the ultra high molecular weight material'sincreased relaxation time (relative to the bulk matrix) causeddistortions in the polymer surface on cooling also leading to lowergloss.

Thus the incorporation lower melting point random propylene/alpha olefincopolymer in the blend compositions of the present invention lowers theoverall melting point, which in turn allows the use of lowerthermoforming temperatures, (that is, lower than that temperature atwhich the gloss begins to increase exponentially). This along with theincorporation of peroxide into these compositions, which also reducesgloss, allows the preparation of embossed parts, which exhibit low glossand excellent embossability, as well as excellent physical properties,including good abrasion and heat resistance.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows position of a thermoform template, with regular raisedcross sections of 0.87 mm height throughout the template, in the bottomof the flat female mold. The screen did not cover the entire area of thethermoformed part.

FIG. 2 shows how embossability can be expressed by thermoforming a sheetsample over an edge with 90° angle. The measurement of embossabilityuses the ratio of the height of the sheet at the mid point of the raisedemboss pattern divided by the distance from this point to the locationat which the sheet returns to the base.

DEFINITIONS

Any numerical values recited herein include all values from the lowervalue to the upper value in increments of one unit provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent or a value of a process variable such as, for example,temperature, pressure, time is from 1 to 90, preferably from 20 to 80,more preferably from 30 to 70, it is intended that values such as 15 to85, 22 to 68, 43 to 51, 30 to 32 etc. are expressly enumerated in thisspecification. For values which are less than one, one unit isconsidered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. These areonly examples of what is specifically intended and all possiblecombinations of numerical values between the lowest value and thehighest value enumerated are to be considered to be expressly stated inthis application in a similar manner.

The term “polymer” as used herein refers to a polymeric compoundprepared by polymerizing monomers whether of the same or a differenttype. The generic term polymer thus embraces the term homopolymer,usually employed to refer to polymers prepared from only one type ofmonomer, and the term interpolymer as defined hereinafter.

The term “interpolymer” as used herein refers to polymers prepared bythe polymerization of at least two different types of monomers. Thegeneric term interpolymer thus includes copolymers, usually employed torefer to polymers prepared from two different monomers, and polymersprepared from more than two different types of monomers.

Statements herein that a polymer or interpolymer comprises or containscertain monomers, mean that such polymer or interpolymer comprises orcontains polymerized therein units derived from such a monomer. Forexample, if a polymer is said to contain ethylene monomer, the polymerwill have incorporated in it an ethylene derivative, that is, —CH₂—CH₂—.

The term “monomer residue” or “polymer units derived from such monomer”means that portion of the polymerizable monomer molecule, which residesin the polymer chain as a result of being polymerized with anotherpolymerizable molecule to make the polymer chain.

Component A—Elastomer

The elastomers, which can be employed as Component A include, but arenot, limited to homogeneously- or heterogeneously-branchedethylene/alpha olefin elastomers and plastomers.

The terms “heterogeneous” and “heterogeneously branched” are used in theconventional sense, and refer to a linear ethylene interpolymer where(1) the α-olefin comonomer is not randomly distributed within a givenpolymer molecule, (2) substantially all of the polymer molecules do nothave the same ethylene-to-comonomer ratio, and (3) the interpolymertypically exhibits a measurable high density (crystalline) polymerfraction as measured by known fractionation techniques such as, forexample, a method that involves polymer fractional elution as a functionof temperature. Commercial examples of heterogeneously branched linearinterpolymers include ATTANE* ULDPE polymers (a product and trademark ofThe Dow Chemical Company) and FLEXOMER™ VLDPE polymers (a product andtrademark of Union Carbide Corporation, a Subsidiary of The Dow ChemicalCompany).

The terms “homogeneous” and “homogeneously-branched” means that in anethylene/α-olefin interpolymer (1) the α-olefin comonomer is randomlydistributed within a given polymer molecule, (2) substantially all ofthe polymer molecules have the same ethylene-to-comonomer ratio, and (3)the interpolymer essentially lacks a measurable high density(crystalline) polymer fraction as measured by known fractionationtechniques such as, for example, a method that involves polymerfractional elution as a function of temperature.

The homogeneously branched ethylene interpolymers that can be used inthe practice of this invention include linear ethylene interpolymers,and substantially linear ethylene interpolymers.

Included amongst the homogeneously branched linear ethyleneinterpolymers useful as elastomers in the compositions of the presentinvention are ethylene polymers which do not have long chain branching,but do have short chain branches derived from the comonomer polymerizedinto the interpolymer which are homogeneously distributed both withinthe same polymer chain and between different polymer chains. That is,homogeneously branched linear ethylene interpolymers have an absence oflong chain branching just as is the case for the linear low densitypolyethylene polymers or linear high density polyethylene polymers madeusing uniform branching distribution polymerization processes asdescribed, for example, by Elston in U.S. Pat. No. 3,645,992. Commercialexamples of homogeneously branched linear ethylene/α-olefininterpolymers include TAFMER™ polymers supplied by the Mitsui ChemicalCompany and EXACT™ polymers supplied by Exxon Chemical Company.

The substantially linear ethylene interpolymers used in the presentinvention are described in U.S. Pat. Nos. 5,272,236 and 5,278,272,6,054,544 and 6,335,410 B1, the entire contents of all of which areherein incorporated by reference. The substantially linear ethyleneinterpolymers useful as elastomers in the compositions of the presentinvention are those in which the comonomer is randomly distributedwithin a given interpolymer molecule and in which substantially all ofthe interpolymer molecules have the same ethylene/comonomer ratio withinthat interpolymer. Substantially linear ethylene interpolymers arehomogeneously branched ethylene polymers having long chain branching.The long chain branches have the same comonomer distribution as thepolymer backbone and can have about the same length as the length of thepolymer backbone. “Substantially linear” means that the bulk polymer issubstituted, on average, with 0.01 long chain branches/1000 totalcarbons (including both backbone and branch carbons) to 3 long chainbranches/1000 total carbons. Preferred polymers are substituted with0.01 long chain branches/1000 total carbons to 1 long chain branch/1000total carbons, more preferably from 0.05 long chain branches/1000 totalcarbons to 1 long chain branch/1000 total carbons, and especially from0.3 long chain branches/1000 total carbons to 1 long chain branch/1000total carbons. Commercial examples of substantially linear polymersinclude the ENGAGE™ polymers (available from DuPont Dow ElastomersL.L.C.), and AFFINITY™ polymers (available from The Dow ChemicalCompany).

Suitable unsaturated comonomers useful for polymerizing with ethylene toprepare suitable heterogeneously- or homogeneously-branched linearethylene interpolymers include, for example, ethylenically unsaturatedmonomers, conjugated or nonconjugated dienes, polyenes, etc. Examples ofsuch comonomers include the C₃-C₂₀ α-olefins such as propylene,isobutylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene,1-octene, 1-nonene, 1-decene, and the like. Preferred comonomers includepropylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene, withoctene-1 being especially preferred. Other suitable monomers includestyrene, halo-or-alkyl-substituted styrenes, tetrafluoroethylenes,vinylbenzocyclobutanes, butadienes, isoprenes, pentadienes, hexadienes,octadienes and cycloalkenes, for example, cyclopentene, cyclohexene andcyclooctene. Typically and preferably, the heterogeneously- orhomogeneously-branched linear ethylene interpolymer is a copolymer inwhich ethylene is copolymerized with one C₃-C₂₀ α-olefin. Mostpreferably, the heterogeneously- or homogeneously-branched linearethylene interpolymer is a copolymer of ethylene and 1-octene or acopolymer of ethylene and 1-butene.

Also included as elastomer component of the compositions of the presentinvention are the substantially random interpolymers comprising polymerunits derived from one or more α-olefin monomers with one or more vinylor vinylidene aromatic monomers and/or a hindered aliphatic orcycloaliphatic vinyl or vinylidene monomers). The substantially randominterpolymers include the pseudo-random interpolymers as described inEP-A-0,416,815 and EP-A-0,765,888 by James C. Stevens et al. and U.S.Pat. No. 5,703,187 by Francis J. Timmers. The substantially randominterpolymers also include the substantially random terpolymers asdescribed in U.S. Pat. No. 5,872,201. Also suitable are thesubstantially random interpolymers, which comprise at least oneα-olefin/vinyl aromatic/vinyl aromatic/α-olefin tetrad disclosed in U.S.Pat. No. 6,191,245 B1.

The substantially random interpolymers can be prepared by polymerizing amixture of polymerizable monomers in the presence of one or moremetallocene or constrained geometry catalysts in combination withvarious cocatalysts. Preferred operating conditions for thepolymerization reactions are pressures from atmospheric up to 3000atmospheres and temperatures from −30° C. to 200° C. Examples ofprocesses used to prepare the substantially random interpolymers aredescribed in U.S. Pat. Nos. 6,048,909 and 6,231,795 B1.

Examples of suitable catalysts and methods for preparing thesubstantially random interpolymers are disclosed in EP-A-0,416,815;EP-A-514,828 (U.S. Pat. No. 6,118,013); EP-A-520,732 (U.S. Pat. No.5,721,185); as well as U.S. Pat. Nos. 5,055,438; 5,057,475; 5,096,867;5,064,802; 5,132,380; 5,189,192; 5,321,106; 5,347,024; 5,350,723;5,374,696; and 5,399,635; 5,470,993; 5,866,704; 5,959,047; 6,150,297;and 6,015,868.

Also included as the elastomer component of the compositions of thepresent invention are ethylene vinyl acetate (EVA), ethylene ethylacrylate (EEA), and ethylene/acrylic acid (EAA) copolymers, rubbers suchas polyisoprene, ethylene/octene, polybutadiene, natural rubbers,ethylene/propylene and propylene/ethylene rubbers, ethylene/propylenediene (EPDM) rubbers, silicone rubbers, styrene/butadiene rubbers andthermoplastic polyurethanes. The elastomer can also be a styrenic blockcopolymer such SBS, SIS, SEBS, CPE, buna rubber, and nitriles.

More preferred elastomers as Component A of the present invention arethe ethylene/alpha olefin and ethylene/vinyl aromatic monomerinterpolymers, with the ethylene/butene, and ethylene/octeneheterogeneously- or homogeneously-branched linear ethylene interpolymersand ethylene/styrene substantially random interpolymers being the mostpreferred.

Component B—Random Propylene/Alpha-Olefin Copolymer

Component B is a random propylene/alpha-olefin copolymer. Preferred arepropylene/C₂-C₂₀ alpha olefin copolymers, Examples of such C₂-C₂₀α-olefins (excluding propylene) include 1-butene, 1-hexene,4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, and thelike. Preferred comonomers include ethylene, 1-butene, 1-hexene,4-methyl-1-pentene and 1-octene, with random propylene/ethylene,propylene/butene, propylene/hexene and propylene/octene copolymers beingmore preferred and random propylene/ethylene copolymers being mostpreferred. The random propylene/alpha olefin copolymer may also be usedas a blend with homopolymer polypropylene in the formulations of thepresent invention. If used as a blend with propylene homopolymer therandom propylene/alpha olefin copolymer component must be present insaid blend in an amount greater than 50, preferably greater than 60,more preferably greater than 70 weight percent, (based on the combinedweight of propylene homopolymer and copolymer).

Component C—Crosslinking Agent

Suitable crosslinking agents include peroxides, phenols, azides,aldehyde-amine reaction products, substituted ureas, substitutedguanidines; substituted xanthates; substituted dithiocarbamates;sulfur-containing compounds, such as thiazoles, imidazoles,sulfenamides, thiuramidisulfides, paraquinonedioxime,dibenzoparaquinonedioxime, sulfur; silanes, ebeam radiation, andcombinations thereof. See Encyclopedia of Chemical Technology, Vol. 17,2nd edition, Interscience Publishers, 1968; also Organic Peroxides,Daniel Seem, Vol. 1, Wiley-Interscience, 1970).

Suitable peroxides include aromatic diacyl peroxides; aliphatic diacylperoxides; dibasic acid peroxides; ketone peroxides; alkyl peroxyesters;alkyl hydroperoxides (for example, diacetylperoxide; dibenzoylperoxide;bis-2,4-dichlorobenzoyl peroxide; di-tert-butyl peroxide;dicumylperoxide; tert-butylperbenzoate; tert-butylcumylperoxide;2,5-bis(t-butylperoxy)-2,5-dimethylhexane;2,5-bis(t-butylperoxy)-2,5-dimethylhexyne-3;4,4,4′,4′-tetra-(t-butylperoxy)-2,2-dicyclohexylpropane;1,4-bis-(t-butylperoxyisopropyl)-benzene;1,1-bis-(t-butylperoxy>3,3,5-trimethylcyclohexane; lauroyl peroxide;succinic acid peroxide; cyclohexanone peroxide; t-butyl peracetate;butyl hydroperoxide; etc. It is also known to those skilled in the artthat the choice of peroxide will also seek to minimize any odor in theresulting final part.

Suitable phenols are disclosed in U.S. Pat. No. 4,311,628. One exampleof a phenolic crosslinking agent is the condensation product of ahalogen substituted phenol or a C₁-C₁₀ alkyl substituted phenol with analdehyde in an alkaline medium, or by condensation of bifunctionalphenoldialcohols. One such class of phenolic crosslinking agents isdimethylol phenols substituted in the para position with C₅-C₁₀ alkylgroup(s). Also suitable are halogenated alkyl substituted phenolcrosslinking agents, and crosslinking systems comprising methylolphenolic resin, a halogen donor, and a metal compound.

Suitable azides include azidoformates, such astetramethylenebis(azidoformate) (see, also, U.S. Pat. No. 3,284,421,Breslow, Nov. 8, 1966); aromatic polyazides, such as4,4′-diphenylmethane diazide (see, also, U.S. Pat. No. 3,297,674,Breslow et al., Jan. 10, 1967); and poly(sulfonyl azides) which are anycompound having at least two sulfonyl azide groups (—SO₂N₃) reactivewith the polymer or polymer blend. Preferably the poly(sulfonyl azide)shave a structure X—R—X wherein each X is SO₂N₃ and R represents anunsubstituted or inertly substituted hydrocarbyl, hydrocarbyl ether orsilicon-containing group, preferably having sufficient carbon, oxygen orsilicon, preferably carbon, atoms to separate the sulfonyl azide groupssufficiently to permit a facile reaction between the polymer or polymerblend and the sulfonyl azide, more preferably at least 1, morepreferably at least 2, most preferably at least 3 carbon, oxygen orsilicon, preferably carbon, atoms between functional groups. Preferredpoly(sulfonyl azide)s include oxy-bis(4-sulfonylazidobenzene),2,7-naphthalene bis(sulfonyl azido), 4,4′-bis(sulfonyl azido)biphenyl,4,4′-diphenyl ether bis(sulfonyl azide) and bis(4-sulfonylazidophenyl)methane, and mixtures thereof.

For crosslinking, the sulfonyl azide is admixed with the polymer orpolymer blend and heated to at least the decomposition temperature ofthe sulfonyl azide, that is usually greater than 100° C. and mostfrequently greater than 150° C. The preferred temperature range dependson the nature of the azide that is used. For example, in the case of4,4′-disulfonylazidediphenylether the preferred temperature range isgreater than 150° C., preferably greater than 160° C., more preferablygreater than 185° C., most preferably greater than 190° C. Preferably,the upper temperature is less than 250° C.

Suitable aldehyde-amine reaction products include formaldehyde-ammonia;formaldehyde-ethylchloride-ammonia; acetaldehyde-ammonia;formaldehyde-aniline; butyraldehyde-aniline; and heptaldehyde-aniline.Suitable substituted ureas include trimethylthiourea; diethylthiourea;dibutylthiourea; tripentylthiourea;1,3-bis(2-benzothiazolylmercaptomethyl)urea; and N,N-diphenylthiourea.Suitable substituted guanidines include diphenylguanidine;di-o-tolylguanidine; diphenylguanidine phthalate; and thedi-o-tolylguanidine salt of dicatechol borate. Suitable substitutedxanthates include zinc ethylxanthate; sodium isopropylxanthate;butylxanthic disulfide; potassium isopropylxanthate; and zincbutylxanthate. Suitable dithiocarbamates include copper dimethyl-, zincdimethyl-, tellurium diethyl-, cadmium dicyclohexyl-, lead dimethyl-,lead dimethyl-, selenium dibutyl-, zinc pentamethylene-, zinc didecyl-,and zinc isopropyloctyl-dithiocarbamate. Suitable thiazoles include2-mercaptobenzothiazole, zinc mercaptothiazolyl mercaptide,2-benzothiazolyl-N,N-diethylthiocarbamyl sulfide, and2,2′-dithiobis(benzothiazole). Suitable imidazoles include2-mercaptoimidazoline and 2-mercapto-4,4,6-trimethyldihydropyrimidine.Suitable sulfenamides include N-t-butyl-2-benzothiazole-,N-cyclohexylbenzothiazole-, N,N-diisopropylbenzothiazole-,N-(2,6-dimethylmorpholino)-2-benzothiazole-, andN,N-diethylbenzothiazole-sulfenamide. Suitable thiuramidisulfidesinclude N,N′-diethyl-, tetrabutyl-, N,N′-diisopropyldioctyl-,tetramethyl-, N,N′-dicyclohexyl-, andN,N′-tetralauryl-thiuramidisulfide.

Those skilled in the art will be readily able to select amounts ofcrosslinking agent, with the amount selected taking into accountcharacteristics of the polymer or polymer blend, such as molecularweight, molecular weight distribution, comonomer content, the presenceof crosslinking enhancing coagents, additives (such as oil) etc.Typically, the amount of crosslinking agent employed will not exceedthat which is required to effect the desired level of crosslinking.

Alternatively, silane crosslinking agents may be employed. In thisregard, any silane that will effectively graft to and crosslink thepolymer or polymer blends can be used in the practice of this invention.Suitable silanes include unsaturated silanes that comprise anethylenically unsaturated hydrocarbyl group, such as a vinyl, allyl,isopropenyl, butenyl, cyclohexenyl or γ-(meth)acryloxy allyl group, anda hydrolyzable group, such as, for example, a hydrocarbyloxy,hydrocarbonyloxy, or hydrocarbylamino group. Examples of hydrolyzablegroups include methoxy, ethoxy, formyloxy, acetoxy, proprionyloxy, andalkyl or arylamino groups. Preferred silanes are the unsaturated alkoxysilanes which can be grafted onto the polymer. These silanes and theirmethod of preparation are more fully described in U.S. Pat. No.5,266,627 to Meverden, et al. Vinyl trimethoxy silane, vinyl triethoxysilane, γ-(meth)acryloxy propyl trimethoxy silane and mixtures of thesesilanes are the preferred silane crosslinkers for use in this invention.

The silane crosslinking agent is grafted to the polymer or polymer blendby any conventional method, typically in the presence of a free radicalinitiator for example peroxides and azo compounds, or by ionizingradiation, etc. Organic initiators are preferred, such as any one of theperoxide initiators, for example, dicumyl peroxide, di-tert-butylperoxide, t-butyl perbenzoate, benzoyl peroxide, cumene hydroperoxide,t-butyl peroctoate, methyl ethyl ketone peroxide,2,5-dimethyl-2,5-di(t-butyl peroxy)hexane, lauryl peroxide, andtert-butyl peracetate. A suitable azo compound is azobisisobutylnitrite. Those skilled in the art will be readily able to select amountsof initiator employed, with the amount selected taking into accountcharacteristics of the polymer or polymer blend, such as molecularweight, molecular weight distribution, comonomer content, as well as thepresence of crosslinking enhancing coagents, additives (such as oil)etc. Typically, the amount of initiator employed will not exceed thatwhich is required to effect the desired level of crosslinking, and isalso employed in an amount so as to result in a reduction in 60° glossat 150° C. by ASTM D523-89 (1999) Standard Test Method for SpecularGloss, (when compared to the same blend composition but absent the crosslinking agent), of at least 50 percent, preferably at least 60 percenteven more preferably by at least 65 percent, most preferably by at least75 percent.

Silane crosslinking is promoted with a crosslinking catalyst, and anycatalyst that will provide this function can be used in this invention.These catalysts generally include organic bases, carboxylic acids, andorganometallic compounds including organic titanates and complexes orcarboxylates of lead, cobalt, iron, nickel, zinc and tin.Dibutyltindilaurate, dioctyltinmaleate, dibutyltindiacetate,dibutyltindioctoate, stannous acetate, stannous octoate, leadnaphthenate, zinc caprylate, cobalt naphthenate; and tin carboxylate,especially dibutyltindilaurate and dioctyltimnaleate, are particularlyeffective for this invention. The catalyst (or mixture of catalysts) ispresent in a catalytic amount, typically between 0.015 and 0.035 weightpercent combined weight of polymer or polymer blend, silane, initiatorand catalyst.

While any conventional method can be used to graft the silanecrosslinker to the polymer or polymer blend, one preferred method isblending the two with the initiator in the first stage of a reactorextruder, such as a Buss kneader. The grafting conditions can vary, butthe melt temperatures are typically between 160° C. and 260° C.,preferably between 190° C. and 230° C., depending upon the residencetime and the half-life of the initiator.

Rather than employing a chemical crosslinking agent, crosslinking may beeffected by use of radiation. Useful radiation types include electronbeam or beta ray, gamma rays, X-rays, or neutron rays. Radiation isbelieved to effect crosslinking by generating polymer radicals, whichmay combine, and crosslink. Additional teachings concerning radiationcrosslinking are seen in C. P. Park, “Polyolefin Foam” Chapter 9,Handbook of Polymer Foams and Technology, D. Klempner and K. C. Frisch,eds., Hanser Publishers, New York (1991), pages 198-204.

Radiation dosage depends upon the composition of the polymer or polymerblend. Those skilled in the art will be readily able to select suitableradiation levels, taking into account such variables as thickness andgeometry of the article to be irradiated, as well as to characteristicsof the polymer, such as molecular weight, molecular weight distribution,comonomer content, the presence of crosslinking enhancing coagents,additives (such as oil), etc.

For instance, in the case of crosslinking of 80 mil plaques by e-beamradiation, typical radiation dosages will be greater than 1 Mrad,preferably greater than 3 Mrad, more preferably greater than 5 Mrad.Electronic radiation dosages are referred to herein in terms of theradiation unit “RAD”, with one million RADs or a megarad beingdesignated as “Mrad”. Typically, the dosage will not exceed that whichis required to effect the desired level of crosslinking. For instance,dosages above 20 Mrad are not typically employed.

A full description of the various cross-linking technologies isdescribed in U.S. Pat. Nos. 5,869,591 and 5,977,271, the entire contentsof both of which are herein incorporated by reference.

In certain embodiments of the claimed invention, dual crosslinkingsystems, which use a combination of radiation, heat, moisture andcrosslinking steps, may be effectively employed. For instance, it may bedesirable to employ peroxide crosslinking agents in conjunction withsilane crosslinking agents, peroxide crosslinking agents in conjunctionwith radiation, sulfur-containing crosslinking agents in conjunctionwith silane crosslinking agents, etc. Dual crosslinking systems aredisclosed and claimed in U.S. Pat. Nos. 5,911,940 and 6,124,370, theentire contents of both of which are herein incorporated by reference.

Component D—Melt Strength Enhancing Polymer

This component is optional and only typically used if the combination ofA, B and C has insufficient melt strength for the application. Typicallythe melt strength required for thermoforming is dependent on a number offactors including the size, thickness and density of the part, thethermoforming temperature, the depth of the draw required for the mold,and any performance requirements in the target application. Thus oneskilled in the art will make the choice of polymer melt strengthenhancer based on the final melt strength required. Component D shouldhave a melt strength of greater than 3 cN and can be, for example, lowdensity polyethylene (LDPE), high density polyethylene (HDPE),polystyrene (PS), natural rubber, ethylene/propylene/diene monomer(EPDM), ultra high molecular weight polyethylene (UHMWPE), and blends ofhigh and low density polyethylene (HDPE/LDPE blends). Most preferred isLDPE with melt strength greater than 3 cN.

Other Additives

Additives can also be included in either the individual blend componentsor added to the final blend. Such additives include antioxidants (forexample, hindered phenols such as, for example, Irganox™ 1010, aregistered trademark of Ciba Geigy), phosphites (for example, Irgafos™168, a registered trademark of Ciba Geigy), U.V. stabilizers, clingadditives (for example, polyisobutylene), slip agents (such as erucamideand/or stearamide), antiblock additives, colorants, carbon black,pigments

Also included as an additive are silicone polymers such as ultra highmolecular weight polydimethylsiloxanes having a minimum molecular weightin the range of 60,000 to 1 million, which can be employed to improveabrasion resistance. These silicone polymers may be added directly butare preferentially added in the form of a masterbatch. Such siloxanemasterbatches are typically dispersed in polymers, for example DowCorning™ MB50-02, which is an ultra high molecular weight siloxanepolymer, dispersed in low density polyethylene and available from DowCorning.

Processing aids, which are also referred to herein as plasticizers, canalso be included in either the individual blend components or added tothe final blend, and include the phthalates, such as dioctyl phthalateand diisobutyl phthalate, natural oils such as lanolin, and paraffin,naphthenic and aromatic oils obtained from petroleum refining, andliquid resins from rosin or petroleum feedstocks. Exemplary classes ofoils useful as processing aids include white mineral oil (such asKaydol™ oil (available from and a registered trademark of Witco), andShellflex™ 371 naphthenic oil (available from and a registered trademarkof Shell Oil Company). Another suitable oil is Tuflo™ oil (availablefrom and a registered trademark of Lyondell).

Also included as a potential component of the polymer compositions usedin the present invention are various organic and inorganic fillers, theidentity of which depends upon the type of application for which theelastic film is to be utilized. The fillers can also be included ineither the individual blend components or added to the final blend.Representative examples of such fillers include organic and inorganicfillers such as those made from asbestos, boron, graphite, ceramic,glass (for example, ground or flaked glass or hollow glass spheres ormicrospheres or beads, whiskers or filaments), metals (such as stainlesssteel, aluminum, bronze, nickel powder, lead or zinc) or polymers (suchas aramid fibers) talc, carbon black, carbon fibers, carbonates such asbarium, calcium or magnesium carbonate; alumina trihydrate, glassfibers, marble dust, cement dust, clay, feldspar, oxides such asaluminum, antimony, B₂O₃, magnesium or zinc oxide, or silicon (e.gsilica or glass, fumed silica) or titanium dioxide; titanates, sulfatessuch as barium or calcium sulfate, aluminum nitride, or chalk, fluoridessuch as calcium or sodium aluminum fluoride; hydroxides such as aluminumhydroxide or magnesium hydroxide; silicates such as aluminum silicate,calcium silicate, asbestos, mica, clay (kaolin or calcined kaolin),feldspar, nepheline, perlite, pyrophyllite, talc or wollastonite;halogenated organic compunds used as flame retardants, metal sulfides;cellulose, in forms such as wood or shell flour; calcium terephthalate;and liquid crystals. Mixtures of more than one such filler may be usedas well.

These additives are employed in functionally equivalent amounts known tothose skilled in the art. For example, the amount of antioxidantemployed is that amount which prevents the polymer or polymer blend fromundergoing oxidation at the temperatures and environment employed duringstorage and ultimate use of the polymers. Such amount of antioxidants isusually in the range of from 0.01 to 10, preferably from 0.05 to 5, morepreferably from 0.1 to 2 percent by weight based upon the weight of thepolymer or polymer blend. Similarly, the amounts of any of the otherenumerated additives are the functionally equivalent amounts such as theamount to render the polymer or polymer blend antiblocking, to producethe desired result, to provide the desired color from the colorant orpigment. Such additives can suitably be employed in the range of from0.05 to 50, preferably from 0.1 to 35, more preferably from 0.2 to 20percent by weight based upon the weight of the polymer or polymer blend.

The blend compositions of the present invention can be used in a varietyof applications including thermoforming, blow molding, injection moldingand overmolding, calendaring, fiber forming, wire and cable, andextrusion coating.

Properties of Blend Composition and Thermoformed Part

Blend Component A—The Elastomer

Component A is present in an amount of from 20 to 80, preferably of from30 to 70, more preferably of from 35 to 65 wt percent (based on thecombined weights of Components A, B, C, and D).

Most preferred is an ethylene/alpha olefin copolymer, which has adensity of less than or equal to 0.915, preferably less than or equal to0.905, most preferably less than or equal to 0.895 g/cm³, or asubstantially random ethylene/vinyl aromatic interpolymer (having avinyl aromatic monomer content of less than or equal to 40, preferablyless than or equal to 30, most preferably less than or equal to 20 molepercent).

Blend Component B—The Random Propylene/Alpha-Olefin Interpolymer

Component B is a random propylene/alpha-olefin interpolymer present inan amount of from 15 to 45, preferably of from 20 to 40, more preferablyof from 20 to 35 wt percent (based on the combined weights of ComponentsA, B, C, and D).

The random propylene/alpha olefin copolymer has an alpha olefin contentsufficient to result in a polymer melting point (Tm) by DifferentialScanning Calorimetry, DSC (as measured by ASTM D-3417) of less than 160,preferably less than 155, most preferably less than 150° C. In the caseof a propylene/ethylene copolymer, the ethylene content is at least 1,preferably at least 2, most preferably at least 3 weight percent basedon the weight of Component B.

Blend Component C—The Crosslinking Agent

Component C is a crosslinking agent, employed in an amount so as toresult in a reduction in 60° gloss at 150° C. (as measured by ASTMD523-89, 1999) of at least 20 percent, preferably at least 30 percenteven more preferably by at least 40 percent, most preferably by at least50 percent, when compared to the same blend composition but absent thecross linking agent.

If the crosslinking agent to be used is a peroxide with a nominal activeoxygen content of 10 percent, then it should be employed in an amount offrom 200 to 6,000, preferably of from 400 to 5,000, more preferably offrom 600 to 4,000 ppm (based on the final weight of the blendcomposition). Those skilled in the art would recognize that theseamounts should be adjusted proportionally if the active oxygen contentof the peroxide differs and/or its concentration differs such as if itis incorporated in an inert polymer, as in a masterbatch formulation.

Blend Component D—The Melt Strength Enhancing Polymer

Component D is present in an amount of from 0 to 40, preferably of from15 to 35, more preferably from 20 to 35 wt percent (based on thecombined weights of Components A, B, C, and D).

Final Blend Properties

The final blend composition should have a peak melting point (Tm) at atemperature of less than 160, preferably less than 155, most preferablyless than 150° C. The lowest Tg peak should be less than −10, preferablyless than −20, most preferably less than −30° C.

Final Thermoformed Part

The thermoformed article should thermoformable at a temperature of lessthan 180, preferably less than 170, most preferably less than 160° C.

The thermoformed article should have a gloss less than 10, morepreferably less than 8, most preferably less than 6 when measured at 60°on textured part using ASTM D523-89 (1999) Standard Test Method forSpecular Gloss).

The thermoformed article should have an Embossability Index of greaterthan 0.48, preferably greater than 0.50, more preferably greaten than0.52.

EXAMPLES Resins and Additives

The properties and description of the resins used in this study can befound in Table 1. The other components were listed in Table 2.

TABLE 1 Physical Characterization of Polymeric Components Used In ThisStudy. Melt Density Flow Polymer (g/cm³) Rate Description AFFINITY*0.870 1.00^(#) Ethylene-octene copolymer, manu- 8100 factured by andavailable from The Dow Chemical Company H700-12 0.900 12.00⁺ Polypropylene homopolymer (Tm 164° C.), manufactured by and availablefrom The Dow Chemical Company 6D65L 0.9000 4.00⁺ Randompropylene/ethylene co- polymer (Tm 143° C.^(♦), 3.7 percent copolymerethylene), manufactured by and available from The Dow Chemical CompanyDS6D82 0.900 7.00⁺ Random propylene/ethylene co- polymer (Tm 134°C.^(♦), 5.7 percent copolymer ethylene, manufactured by and availablefrom The Dow Chemical Company LDPE 526A 0.922 1.00^(#) Low densitypolyethylene, manu- factured by The Dow Chemical Company ^(#)Measured at190° C./2.16 kg; ⁺Measures at 230° C./2.16 kg; *a trademark of The DowChemical Company ^(♦)Tm measured by ASTM D-3417

TABLE 2 Characterization of Additional Components Used In This Study.Active Product percent Additive form by wt. Description Carbon blackPellet 50 Carbon black in polypropylene masterbatch carrier availablefrom Ampacet Irganox B225 Powder 100 50/50 Blend of Irganox* 1010 andIrgaphos* 168. Huber F325 Powder 100 Calcium carbonate filler availableCaCO₃ from Huber Corporation Zinc Powder 100 Available from AldrichChemical stearate Company. Luperox Powder 20 20 percent active peroxide101PP20 dispersed on polypropylene powder, 2.2 percent active oxygen.Available from Ato Fina. *A trademark of Ciba GiegyCompounding

Compounding was done using a computer-controlled 40 mm, 34:1 L/DWerner-Pfliderer 50 horsepower twin screw extruder. The components weredry blended together and fed into the twin screw. The screw designprovided moderate mixing and shear, ensuring homogeneous extrudate. The7-zone extruder was starve-fed to produce 100 pounds per hour at a melttemperature of approximately 215° C. The extruder profile was set at185-195-200-200-205-205° C. The polymer exited the extruder through asingle strand die and was quenched in a water bath and then pelletized.Typically, a total of 100 pounds of each blend was produced. Thecomposition of the compounds was shown in Table 3.

TABLE 3 Composition of Blends Used In This Study^(#) Blend Blend BlendBlend Blend Blend Polymers 1 2 3 4 5 6 H700-12 PP 0.00 0.00 10.95 10.9522.05 21.91 6D65L 21.91 0.00 10.95 0.00 0.00 0.00 DS6 D82 0.00 21.910.00 10.95 0.00 0.00 AFFINITY* 43.81 43.81 43.78 43.78 44.10 43.81 8100LDPE 526A 21.91 21.91 21.89 21.89 22.05 21.91 Ingredient 0.00 0.00 0.000.00 0.00 0.00 CB/PP MB 1.31 1.31 1.31 1.31 1.32 1.31 Irgonox B225 0.260.26 0.26 0.26 0.26 0.26 F325 CaCO3 9.94 9.94 9.99 9.99 10.00 9.94 ZnStearate 0.22 0.22 0.22 0.22 0.22 0.22 Luperox 0.65 0.65 0.65 0.65 0.000.65 101PP20 (ppm (1300) (1300) (1300) (1300) (0) (1300) Peroxide⁺)Total = 100.00 100.00 100.00 100.00 100.00 100.00 ^(#)All values wereweight percent unless stated; ⁺Peroxide level corrected to undilutedconcentration (Luperox 101PP20 was a 20 percent peroxide/polypropyleneconcentrate).Thermoforming Evaluations and Gloss Measurements

The sheet to be thermoformed was made by extruding the pellets producedon the compound line through a computer-controlled 2 inch 30:1 L/D 5zone Killion extruder through a 28-inch die gapped at 60 mils. Theextruder screw speed was maintained at around 75 rpm. Extrudate melttemperature was approximately 168° C. The thickness of the sheet wasmaintained by varying the speed of the take away with a nominalthickness of 125 mils. The downstream equipment consisted of roll stackwith three 12-inch diameter by 30-inch wide chrome plated rolls that fedinto an air shear cutter made by Wysong.

Thermoforming was accomplished by using an AAA cut sheet thermoformer.This cut sheet thermoformer had ceramic heaters that heated the sheet ofplastic after it was shuttled into the oven. Each sample was held in theoven, for varying times prior to thermoforming (between 60, 90, 100,110, 120, 150 and 180 seconds) and the sample temperature was thenobtained by constructing a calibration curve of time in the oven vs.sample sheet temperature. The longer the sample was held in the oven,the higher the temperature of the removed sheet. The measured sheettemperature was consistent between the various samples for a givenlength of time in the oven. After heating, the sheet was removed fromthe oven and immediately vacuum-formed into an air-cooled mold.

In order to evaluate gloss, and how well any emboss pattern wastransferred to the sheet during thermoforming, a thermoform templatewith regular raised cross sections of 0.87 mm height throughout thetemplate, was placed in the bottom of the flat female mold. Since theability of the polymer sheet to thermoform was a function of thetemperature of the sheet, for each thermoforming experiment thetemperature of the samples was varied between a low value up to thepoint where the screen “stuck” to the film during the forming process.The screen did not cover the entire area of the thermoformed part, FIG.1.

All gloss readings were obtained using ASTM D523-89 (1999) Standard TestMethod for Specular Gloss using a Gardner BYK micro-TRI-gloss meter.Gloss was measured at 60° and the values reported represent the averageof 4 readings. The gloss readings were obtained from areas where thescreen hit the sample that was from the textured area. The gloss valuesfrom the textured area of a thermoformed sheet were measured as afunction of the sample temperature at thermoforming. Table 4 summarizesthe 60° gloss values of the textured area of the thermoformed sheet as afunction of temperature.

TABLE 4 60° Gloss of Textured Area of Thermoformed Sheet as a Functionof Temperature. Blend 60° Gloss 60° Gloss 60° Gloss 60° Gloss 60° Gloss60° Gloss Ex # Used At 115° C. At 148° C. At 152° C. At 159° C. At 172°C. At 184° C. Ex 1 Blend 1 1.6 2.5 2.9 3.3 7.9 9.8 Ex 2 Blend 2 1.9 2.22.1 2 6.6 11.2 Ex 3 Blend 3 1.8 2.4 2.7 2.9 3.3 10.1 Ex 4 Blend 4 2.02.2 2.3 2.2 5.9 12.7 Comp Ex 1 Blend 5 2.1 2.4 3 10.8 15.7 12.6 Comp Ex2 Blend 6 1.7 1.6 2.4 3.7 8.8 9.6Embossability Index

Thermoform embossability refers to the shape conformability of athermoform sheet to a template after the thermoforming operation thatis, the ability to reproduce the shape or pattern of a given template asreflected in the final thermoformed article. FIG. 2 shows howembossability can be expressed by thermoforming a sheet sample over atemplate with an edge with a 90° angle. The measurement of embossabilityindex uses the ratio of the height of raised emboss pattern divided bythe distance from which the slope of the emboss pattern varies from theperpendicular as shown in FIG. 2. The Embossability Index (EI) was anormalized scale, which can thus be used to designate the extent of theembossability of the thermoform sheet samples. It was expressed asEquation 1:

$\begin{matrix}{{EI} = {1 - \frac{1}{{\mathbb{e}}^{H/L}}}} & ( {{Equation}\mspace{14mu} 1} )\end{matrix}$

Improved embossability results from maximizing the height (H) andminimizing the length (L). Thus the ratio of H/L increases as the sampleapproaches perfect pattern assimilation or reproduction of the embosspattern. For example, a ratio of H to L that equals 0.5 would result inan EI value of 0.393. As the ratio of H/L increases to 1, the EIincreases to a value of 0.638. Table 5 summarizes the embossabilityindex as a function of temperature of thermoformed sheets made fromblends used in this study, Acceptable Embossability Index values weredefined as those with EI greater than 0.50.

TABLE 5 Embossability Index as a Function of Temperature of ThermoformedSheets Made From Blends Used In This Study. Blend Used for TemperatureEmbossability Example # Sheet (C.) Index* Ex 5 Blend 1 144 0.60 154 0.67Ex 6 Blend 2 139 0.49 145 0.61 156 0.73 Comp Ex 3 Blend 5 144 0.39 1570.42 Comp Ex 4 Blend 6 143 0.36 159 0.41 *Acceptable Embossability Indexvalues were values greater than 0.48.

Analysis of the gloss levels in Table 4 for Comparative Example 1, whichhas no peroxide, shows a significant and sharp increase in gloss above159° C. Although the gloss levels in Examples 1-4 also show asignificant and sharp increase in gloss, this occurs at a highertemperature range that is, between 159 and 172° C.

Analysis of the Embossability Index data in Table 5, shows that forsamples containing the random propylene/ethylene copolymer and peroxide(that is, Examples 5 and 6), the EI values were all acceptable (thatis, >0.5) at thermoforming temperatures between 144-156° C. However,Comparative Example 4, the analogous blend, but where Component B wasonly homopolymer polypropylene instead of random polypropylene,acceptable EI values were not achieved even at temperatures as high as159° C. Also, analysis of the EI data for Comparative Example 3, whichcontains the homopolymer polypropylene but no peroxide, shows that thiscomposition still did not achieve acceptable EI values even attemperatures of 157° C. This was even though the absence of peroxideshould improve the flow characteristics of the sheet and thus improveembossability.

Thus, the incorporation of random polypropylene into the compositions ofthe present invention increases their ability to be thermoformed at atemperature that was lower than that at which the gloss begins toincrease exponentially. This reduction in temperature when coupled withthe addition of peroxide into these compositions also reduces gloss,allowing the preparation of embossed parts, which exhibit both low glossand excellent embossability. It should also be noted that when a blendof homopolymer polypropylene and random propylene/ethylene copolymer wasused as Component B, a similar enhancement in both gloss andembossability was also observed.

1. A polymer blend consisting of the following: A) an elastomer selectedfrom a homogeneously- or a heterogeneously-branchedethylene/alpha-olefin interpolymer having a density of less than, orequal to, 0.905 g/cm³; B) a random propylene/ethylene copolymer having amelting point (Tm) by Differential Scanning Calorimetry (as measured byASTM D-3417) of less than 160° C.; C) from 200 ppm to 1300 ppm, based onthe weight of the composition, of a peroxide crosslinking agent; and D)a melt strength enhancing polymer which is a is low density polyethylene(LDPE) with a melt strength of greater than 3 cN; and E) at least oneadditive selected from the group consisting of antioxidants, phosphites,U.V. stabilizers, cling additives, slip agents, antiblock additives,plasticizers, colorants, pigments, carbon black masterbatch, organicfillers, inorganic fillers, silicon polymer, and combinations thereof;and wherein the blend has an Embossability Index (EI) greater than 0.48,at thermoforming temperatures from 144° C. to 156° C., and wherein theblend does not contain a free radical coagent.
 2. The blend of claim 1,wherein A) said elastomer, Component A, is present in an amount from 20to 80 weight percent (based on the total weight of Components A, B, C,and D); B) said random propylene copolymer, Component B, is present inan amount from 15 to 45 weight percent (based on the total weight ofComponents A, B, C, and D), and has a melting point (Tm), as measured byASTM D-3417, of less than 160° C.; C) said cross linking agent,Component C, is employed in an amount, so as to result in a reduction in600 gloss at 150° C., by ASTM D523-89 (1999), of at least 20 percent, ascompared to the same blend composition, but absent the cross linkingagent, and D) said melt strength enhancing polymer, Component D, ispresent in an amount from 15 to 35 weight percent (based on the totalweight of Components A, B, C, and D); and wherein E) said blend has apeak melting point, (Tm), as measured by Differential ScanningCalorimetry, DSC, using ASTM D-3417, of less than 165° C., and has alowest Tg peak of less than −10° C.
 3. The blend of claim 1, wherein A)said elastomer, Component A, is present in an amount from 30 to 70weight percent (based on the total weight of Components A, B, C, and D);B) said random propylene copolymer, Component B, is present in an amountfrom 20 to 40 weight percent (based on the total weight of Components A,B, C, and D), and has a melting point (Tm), as measured by ASTM D-3417,of less than 155° C.; C) said cross linking agent, Component C, isemployed in an amount, so as to result in a reduction in 600 gloss at150° C., by ASTM D523-89 (1999), of at least 30 percent, as compared tothe same blend composition, but absent the cross linking agent; and D)said melt strength enhancing polymer, Component D is present in anamount from 15 to 35 weight percent (based on the total weight ofComponents A, B, C, and D); and wherein E) said blend has a peak meltingpoint (Tm), as measured by Differential Scanning Calorimetry, DSC, usingASTM D-3417, of less than 160° C., and has a lowest Tg peak of less than−20° C.
 4. The blend of claim 1, wherein A) said elastomer, Component A,is present in an amount from 35 to 65 weight percent (based on the totalweight of Components A, B, C, and D); B) said random propylenecopolymer, Component B, is present in an amount from 20 to 35 weightpercent (based on the total weight of Components A, B, C, and D), andhas a melting point (Tm), as measured by ASTM D-3417, of less than 150°C.; C) said cross linking agent, Component C, is employed in an amount,so as to result in a reduction in 600 gloss at 150° C., by ASTM D523-89(1999), when compared to the same blend composition, but absent thecross linking agent, of at least 40 percent; and D) said melt strengthenhancing polymer, Component D is present in an amount from 20 to 35weight percent (based on the total weight of Components A, B, C, and D);and wherein E) said blend has a peak melting point, (Tm), as measured byDifferential Scanning Calorimetry, DSC, using ASTM D-3417, of less than155° C., and has a lowest Tg peak of less than −30° C.
 5. A polymerblend consisting of the following: A) an elastomer selected from ahomogeneously- or a heterogeneously-branched ethylene/alpha-olefininterpolymer having a density of less than, or equal to, 0.905 g/cm³; B)a mixture of polypropylene homopolymer and random propylene/ethylenecopolymer having a melting point (Tm) by Differential ScanningCalorimetry (as measured by ASTM D-3417) of less than 160° C.; C) from200 ppm to 1300 ppm, based on the weight of the composition, of aperoxide crosslinking agent; D) a melt strength enhancing polymer whichis a is low density polyethylene (LDPE) with a melt strength of greaterthan 3 cN; and E) at least one additive selected from the groupconsisting of antioxidants, phosphites, U.V. stabilizers, clingadditives, slip agents, antiblock additives, colorants, pigments,plasticizers, carbon black masterbatch, organic fillers, inorganicfillers, silicon polymer, and combinations thereof; and wherein theblend has an Embossability Index (EI) greater than 0.48, atthermoforming temperatures from 144° C. to 156° C., and wherein theblend does not contain a free radical coagent.
 6. The polymer blend ofclaim 1 or claim 5, wherein the at least one additive is selected fromthe group consisting of a siloxane polymer, carbon black or inorganicfiller, or a combination thereof.
 7. A molded part comprising the blendof claim 1 or
 5. 8. A thermoformed part comprising the blend of claim 1or
 5. 9. A wire and cable jacket comprising the blend of claim 1 or 5.10. The part of claim 8, wherein the part is in the form of anautomotive floor or floor mat.
 11. A polymer blend consisting of A) anelastomer selected from a homogeneously- or a heterogeneously-branchedethylene/alpha-olefin interpolymer having a density of less than, orequal to, 0.905 g/cm³; B) a random propylene/ethylene copolymer having amelting point (Tm), by Differential Scanning Calorimetry DSC (asmeasured by ASTM D3417), of less than 160° C.; C) from 200 ppm to 1300ppm, based on the weight of the composition, of a peroxide crosslinkingagent; D) at least one additive selected from the group consisting ofantioxidants, phosphites, U.V. stabilizers, cling additives, slipagents, antiblock additives, colorants, pigments, plasticizers, carbonblack masterbatch, organic fillers, inorganic fillers, silicon polymer,and combinations thereof; and optionally, E) a melt strength enhancingpolymer which is a is low density polyethylene (LDPE) with a meltstrength of greater than 3 cN; and wherein the blend has anEmbossability Index (EI) greater than 0.48, at thermoformingtemperatures from 144° C. to 156° C., and wherein the blend does notcontain a free radical coagent.
 12. An article comprising at least onecomponent formed from the composition of claim
 1. 13. An articlecomprising at least one component formed from the composition of claim11.
 14. A polymer blend consisting of the following: A) an elastomerselected from a homogeneously- or a heterogeneously-branchedethylene/alpha-olefin interpolymer having a density of less than, orequal to, 0.905 g/cm³; B) a mixture of a polypropylene homopolymer and arandom propylene/ethylene copolymer having a melting point (Tm), byDifferential Scanning Calorimetry DSC (as measured by ASTM D3417), ofless than 160° C.; C) from 200 ppm to 1300 ppm, based on the weight ofthe composition, of a peroxide crosslinking agent; D) at least oneadditive selected from the group consisting of antioxidants, phosphites,U.V. stabilizers, cling additives, slip agents, antiblock additives,colorants, pigments, plasticizers, carbon black masterbatch, organicfillers, inorganic fillers, silicon polymer, and combinations thereof;and optionally, E) a melt strength enhancing polymer which is a is lowdensity polyethylene (LDPE) with a melt strength of greater than 3 cN;and wherein the blend has an Embossability Index (EI) greater than 0.48,at thermoforming temperatures from 144° C. to 156° C., and wherein theblend does not contain a free radical coagent.
 15. The blend of claim 1,wherein the random propylene/ethylene copolymer has a melting point (Tm)by Differential Scanning Calorimetry (as measured by ASTM D-3417) ofless than 150° C.
 16. The composition as in claims 1, 5, 11 or 14,wherein the elastomer is a homogeneously branched ethylene/alpha-olefininterpolymer having a density of less than, or equal to, 0.905 g/cm³.17. The composition as in claims 1, 5, 11 or 14, wherein, for theelastomer, the alpha-olefin is selected from propylene, 1-butene,1-hexene, 4-methyl-1-pentene or 1-octene.